An electronic document file may include various types of objects, such as text, line art, and images, which may be generated and edited by a user on a computer system with graphics application software. Most graphics application software can also be used to produce printed output defined by the electronic document file.
In some cases, the objects on a page of an electronic document file may be transparent, with varying degree, so that objects that are placed behind the transparent objects can be seen through the transparent objects. When a user wishes to generate a printed copy of the electronic document file, the file is converted into a format that can be understood by a printing device in a process generally referred to as rendering. If an electronic document file contains a combination of transparent and opaque objects, the objects on each page of the electronic document file are broken up into opaque pieces, also referred to as atomic regions, during the rendering process, so that they may be printed on the printing device; this process is known as flattening.